Oil recovery process



nun awum- H M H V v w W June 18, 1957 c. w. BRANDON OIL RECOVERY PROCESS5 Sheets-Sheet 1 Filed Aug. 15, 1951 randan TOR.

June 18, 1957 c. w. BRANDON on. RECOVERY PROCESS 5 Shee ts-Sheet 2 FiledAug. 15, 19 51 llnilz 1/1 I m g Clarence W. Brandon INVEN TOR.

June 18, 1957 c. w. BRANDON v 2,796,129

011. RECOVERY PROCESS Filed Aug. 13, 1951 5 SheetsSheet 3 Fig.3.

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Clarence M Brandah June 13, 1957 c, w, BRANDON 2,796,129

OIL RECOVERY PROCESS 5 Sheets-Sheet 4 Filed Aug. 13. 1951 Fig.5-

G/arente W Brandon INVENTOR.

M EM L June 18, 1957 c. w. BRANDON 2,795,129

. OIL RECOVERY PROCESS 4 Filed Aug. 13, 1951 S 'Sheets-Sheet 5 C/arenceW Brandon INVENTOR,

OIL RECOVERY PROCESS Clarence W. Brandon, Tallahassee, Fla, assignor ofoneeighth to Orpha B. Brandon, Tallahassee, Fla., and one-half to N. A.Hardin, Catherine H. Newton, and Hazel H. Wright, all of Forsyth, Ga.,and one-twentieth to Harvey B. Jacobson, Washington, D. C.

Application August 13, 1951, Serial No. 241,647

9 Claims. (Cl. 166) This invention comprises novel and usefulimprovements in oil recovery processes and more specifically pertains toimproved methods tor recovering oil and petroleum deposits frompetroliferous strata with a greater efiiciency than heretofore possible;and especially pertains to effecting a substantially complete recoveryof the residual mobile oil and petroleum deposits remaining in oilbearing sands of either the Cenozoic or Paleozoic formations afternormal oil producing methods, including re-pressuring, water drives andthe like have been completed.

It is well known in the petroleum producing industry that normally lessthan 30% of the mobile petroleum deposits of a Paleozoic field areremoved by normal well drilling operations; and not more than anadditional 35% are recoverable by presently known water drive methods ofproduction, leaving at least 35% of the original total mobile depositsretained in the oil bearing strata and heretofore impossible ofreclaiming.

The present almost universal practice of dealing with this condition isto employ a water drive which consists in repressuring the oil strataiormation with water under any desired pressure from one or more wellbores, and to attempt, by this pressure, to drive the oil globules toadjacent well bores where the same may be withdrawn. As above pointedout, this practice is successful to the ex tent :of, at most, anadditional one-half of the 70% of the original oil deposit left by theusual preceding oil well producing methods.

In coping with the .above mentioned conditions and problems, I utilize amechanical under-cutting of the productive formation together with wavepulsations of various irequencies as a means for applying energy atdesired places within the strata.

An additional object is to controllably vary the elasticity of :atransmitting medium to thereby alter the vibrational characteristics .ofwave pulsations applied thereto.

More specific objects of the invention, in conformity with the precedingobjects, are to produce a resultant wave pulsation in a medium havingmore perfect directional control; having an extremely effectivedisruptive effect upon cellular formation and porous bodies of allcharacters; having a minimum transmission loss of energy between theplace of generation and the place of use.

A further extremely important object is to eifeotively control and causethe flow of iluids within a porous or cellular formation by theapplication of high frequency wave pulsations applied thereto through afluid pressure medium.

Another extremely important object, in accordance with the immediatelypreceding object, is to provide a method of disrupting porous orcellular iormations by the application of high frequency wave pulsationthereto of controllable amplitude and/or pitch through a fluid pressuremedium.

An important object of the invention is to provide a method as set forthin the foregoing objects in which it shall be possible to physicallymine and remove the oil sands from the oil strata, either all or inpart, as desired,

atent C er 1C in order to obtain samples, for subjecting the sands soremoved to any desired process or treatment for recovering the immobileoil particles adhering thereto, and to provide cavities in the formationby the removal of these sands to facilitate the application of treatingmediums thereto and especially the subjecting of the strata topulsations of high frequencies.

An additional object of the invention is to provide a method inaccordance with the proceding objects which shall effectively wash thesand formation with water, oil or any other desired fluid medium toeffectively strip the mobile and the immobile oil particles from thesand strata; and to impose upon this washing action high frequencypulsations in both the washing medium and in the sand strata to renderthe washing action more efiective.

Yet another very important object of the invention is to provide amethod as hereinbefore set iorth which shall admit of the gravelling of.a sand formation either alone or in conjunction with any of the abovenoted operations; and especially as regards Cenozoic deposits forpreventing clogging of the oil drainage passages by sand and the like.

A still further important object of the invention is to provide a methodwhereby a mechanical cutting agent may be applied to the lower portionof a petroliferous strata of the Paleozoic type for severing orundercutting the same to elfect :a subsequent disruption of thecapillary formation; and wherein and/or when the mechanical cuttingmeans is applied in operative position to the strata formation, itsaction will be assisted by the introduction of gases into the formationand/or through the agency of high frequency pulsations in a hydrauliccutting medium and impressed upon the gases to control their gaseous andliquid phase and thus their rupturing effect.

A still further important object of the invention is to provide an oilrecovery method for the depleted oil deposits wherein selected portionsof the lower part of an oil bearings and strata may be physically orhydraulically undercut and/ or removed and replaced by gravel tofacilirate the drainage of oil from the overlying sand formation.

Yet another object of the invention is to provide a method whereinvarious predetermined portions of an oil strata may be undercut andremoved leaving selected portions to remain as supports for the rest ofthe strata for later removal, with a view to undercutting, breaking bythe disruptive effect of controllably varied internal pressures in thestrata; or removing the strata in accordance with known geologicalcontours of the strata to effect more efficient drainage and recovery ofoil therefrom.

Figure l is a diagrammatic perspective view, partly shown in section,illustrating the manner in which a mechanical cutting cable or otherdevice may be employed for undercutting an oil strata through aplurality of well bores;

Figure 2 is a fragmentary top plan view of a portion of an oil fieldshowing in top plan the arrangement of Figure 1, parts being broken awayo show the different stratas of the field;

Figure 3 is a diagrammatic plan view of a portion of :an oil fieldillustrating various manners of undercutting the field in accordancewith my method;

Figure 4 is a diagrammatic View in vertical section through a portion ofan oil field formation, showing the preliminary stages in the tunnelingoperation of Figure 1;

Figure 5 is :a diagrammatic top plan view of a portion of an oil fieldillustrating the simultaneous tunneling and strata disrupting operationsbetween a plurality of wells;

Figure 6 is a vertical sectional view, somewhat diagrammatic and withparts broken away, of an apparatus for effecting the hydraulic operationand causing the compounded high firequency vibrations utilized in thisinvention;

3 Figure 7 is a detail view of a part of the apparatus of Figure 6.

Mechanical undercutting of strata Figures 1 and 2 disclosediagrammatically one exemplification of the manner in which theprinciples of this invention may be applied to the recovery of oil froma strata by physically disruping and/or undercutting the same andreleasing the capillary lock by which mobile oil globules are held inthe interstices of the sand formation. Shown in Figures 1 and 2 is atypical sand formation of a Paleozoic oil field wherein the numeral 10designates the oil bearing strata, while the numerals 12 and 14respectively indicate the cap rock and the bedrock layers of the oilsand formation.

In the example illustrated, the method is to be applied to an oil fieldin which the normal methods of production, including repressuring by thepossible previous use of a water drive method of reclaiming oil havebeen applied and the flow of the field has now ceased, or reached a rateof production which is no longer profitable. Indicated at 16 and 18 area pair of well bores which, in conjunction with the well bore 20, aredisposed in a triangular relation.

In accordance with this method of my invention, these existing andpossibly abandoned well casings and bores are utilized in order toobtain preliminary access to the oil bearing sand strata 10 at a minimumcost, at a maximum convenience and saving in time, as well as to enableeffective use of information available from previous operation of thisoil field regarding the geological formation of the same. It is ofcourse apparent that I may drill original bores into the formationwherever found to be desirable; and may apply my methods tounderdeveloped fields. It is proposed to establish tunnels 22 and 24which respectively communicate the intermediate well casing or bore 20with the two oppositely positioned casings or bores 16 and 18, below thetop surface of and preferably at the bottom surface of the oil sandstrata 10, substantially upon the bedrock 14.

The principles of this method of the invention are not limited to anyparticular way for effecting the formation of the tunnels 22 and 24,since various known subterranean tunneling methods or apparatuses may beemployed. As set forth hereinafter, hydraulic methods of tunneling aredeemed to be peculiarly efficacious in oil fields of this character.

It will of course be understood that the tunnels 22 and 24 will notnecessarily be directed in straight lines between the well casings orbores, but may obviously be of irregular pattern, as shown in Figure 2.Where hydraulic tunneling methods are employed, as set forth hereafter,the tunneling will preferably follow the path of least resistance andprevious water drive operations, insofar as they have previouslyestablished subterranean passages, will probably be of advantagetherein. However, my method also comprehends a directional tunnelingaction as set forth hereafter. Actually, the straightness orirregularity of these tunnels is of little consequence or importance inthe present method, it being merely necessary that a tunnel passagewaybe established between the wells in the manner suggested.

Once the tunnels have been established, a physical sand cutting means isintroduced into and passed through these tunnels, this cutting meansbeing indicated at 26 as consisting of a cutting cable or chain of anydesired character and which has one end portion extending downwardlythrough a well casing or bore 16 and from thence through the tunnels 22and 24, and having its other portion extending upwardly through thecasing or bore 18.

While undoubtedly numerous ways can be devised for inserting the cuttingdevice in the tunnels, I deem the following to be simple and effective.A lead line with floats will be inserted to the bottom of a well boreand then fed by water flow through the tunnels and up the selected bore.The lead line will provide a means for drawing the cutting cable throughthese passages.

Suitable cable guiding means 28 will be provided at the bottoms of thewell bores 16 and 18 in order to position the cable horizontally acrossthe face of the oil sand strata 10 and prevent reciprocation of thecable at its turns from damaging the well casings. Since it will berecognized that many different types of cutting devices and guidingmeans therefor may be provided, and as my invention is not limited toany particular structural arrangement of the same, detailed explanationand illustration appears to be unnecessary.

The cutting device may be either a member having loose ends, each ofwhich is connected to a reciprocating member 30, caused to verticallyreciprocate from any suitable power source, not shown, whereby theentire cable will be given a reciprocating or sawing motion, or thecable may be in the form of a continuous or endless band or cuttingmember and may be given a continuous rotation.

In either event, it will now be apparent that upon actuation of thecable by either reciprocation or rotation of the same, that portion ofthe cable contacting the face of the sand strata 10 will abrade, cut andsaw the same. By virtue of the angular relationship of the cablesections between the casing 20 and the two casings 16 and 18, it will beevident that the cable will undercut the sand strata until eventuallythe cable will be disposed at a substantially straight line between thecasings 16 and 18, in a manner which will be apparent from Figure 2.

This triangulation method may obviously be continued through the fieldby progressing to successive well bores until the entire field iscovered.

It is worthy of note at this point that the oil strata has an internalpressure, frequently retained therein at substantially its originalvalue by the above described capillary lock, which causes the face ofthe formation to burst outwards as the same is weakened by the cuttingdevice. This outflow of oil, water and gases serves to wash the cuttingdevice and the face of the strata, facilitating the cutting operation.It is within the intent of this invention to increase or vary theinternal pressure as set forth hereafter.

However, alternative methods of undercutting the entire field either bysections or by a cut across the entire width of the field may beemployed. As previously described in connection with Figures 1 and 2,the entire area of the field may be covered as a series of steps, eachstep utilizing a triangular arrangement of well bores. During thistriangular method of cutting, adjacent well bores may be'utilized as thethree corners of a triangle; or relatively greater spaced wells maylikewise be used, the cutting proceeding from the three corners as abovementioned.

As shown in full lines in Figure 3, a strip method of cutting ispossible. Thus, the cutting device may be inserted down a well bore, asat D, then connected by tunnels to the wells at A, B and E and up thewell bore at E, thus disposing the cutter in a U-shaped arrangement.When the cutting device has reached a position across D, E or hassubstantially reached such a position, the operation may be repeated forthe well bores G, D, E and H, as shown in dash lines in Figures 3, thuscutting in a step-by-step arrangement an entire longitudinal strip.Alternatively, the cutting device could be disposed substantially alongthe entire row of wells, A, D, and G and the other wells along thisline, then across the end of the oil fields at the well A and B, thendown the row of well B, E, H to the end of that row of wells, the endsof the cable passing up through the end wells of each row. Thus, asingle cutting device and in a single cutting operation an entire stripof the oil field could be undercut.

Finally, however, it is evident that the cable or cutting device couldbe disposed across the entire width of the oil field, as shown in dashand dot lines in Figure 3, as by running the intermediate portions ofthe cables between the wells D, A, B, C, F, with the ends of the cablescoming up through the well bores D and F for operation. The entire oilfield could then be cut in a step-by-step manner, as above set forth,the operating ends of the cables being successively moved back to wellsG and I and so forth, until the entire field is traversed. Finally,however, in some instances, the sides of the cable could extend alongthe entire length of the field as through the wells D, A, G on one sideand the wells C, F and I, and so forth on the other side, or amid-portion of the cable be inserted across the width of the field, asbetween the wells A, B and C.

As will thus be apparent, this method will effectively permit theemployment of a different arrangement for undercutting an oil strata.

With any of the above methods of cutting, it is evident that the cablemay be worked at different vertical levels. Thus, in very thick oilstrata, it may be preferred to make the initial undercutting operationat the bedrock of the strata; and make successive horizontal cutsbetween the bedrock and the cap rock in accordance with the characterand dimensions of the formation. This can be readily done by merelyraising the guide rollers supporting the cable at the bottom of the Wellbores through which the cable ends are operated, to thereby position thehorizontal section of the cable at the desired elevation in the oilstrata.

It will be particularly noted that the above described method enablesthe partial or complete undercutting of the sand formation, thusenabling the superincumbent strata to collapse either under its ownweight or under the assistance of jars and shocks applied thereto in anydesired manner. The collapsing of the sand strata above the undercuttingwill obviously disrupt the capillary formation thereof, permittingdrainage of the mobile oil particles contained therein, under theinfluence of gravity, to the bottom of the undercutting channel, fromwhence the oil may be readily removed from the ground in any desiredmanner.

Even if the undercutting above mentioned does not cause collapse anddropping of the strata, it will facilitate the draining of oil from thestrata downwardly under the influence of gravity into the undercuttingchannel which would constitute an oil collecting basin, the extent ofthis drainage depending upon the effectiveness of the capillary block inthe superposed formation.

The method as hereinbefore set forth further envisions and contemplatesthe physical removal of that portion of the sand strata which has beenremoved by the cutting means 26, and it is possible to withdraw the sandso removed either by the physical action of the cutting means 26, orthrough the agency of various carrying mediums, such as oil, water, orthe like, thereby providing clearance space which will facilitate andpermit the collapse of the superposed strata.

It will now be readily understood that by the above described methods ofcutting, that various predetermined portions of the oil strata may beundercut leaving untouched columns which will support the rest of thestrata. This will enable the operator to undercut and disrupt the strataformation, establish drainage channels and passages to the bestadvantage in accordance with topographical conditions existing in theoil strata and the like.

In some instances, it may be preferred to replace the sand cut away bythe cutting means 26 by filling this space behind the cutting means withgravel or the like. This gravel fill will, upon collapse of theoverlying strata, provide a drainage means permitting the flow of oilfrom the broken capillary formation of the disrupted strata toward theoil lifting and discharging means of the operation.

I wish it to be clearly understood that the foregoing methods are tosome extent applicable to all types of oil formations and also areuseful at all stages of the development of an oil field, from prior toits first producing well until repressur-ing operations have ceased toproduce profitably. However, I have emphasized its use in Paleozoicformations, since the foregoing method, as well as those to behereinafter set forth, represents to date the only feasible method ofreclaiming any appreciable portion of the last 35% of the original oildeposits necessarily abandoned in these formations by heretofore knownmethods of oil recovery.

Further, the present invention constitutes processes which will permitand facilitate recovery of both the mobile and immobile oil and in boththe absorbed and adsorbed conditions.

Hydraulic tunneling means and method Attention is now directed moreparticularly to Figures 4 and 6 for an explanation and understanding ofa preferred manner of establishing tunnels between predetermined wellbores. From a predetermined oil well casing of a selected well bore, orfrom a new bore provided for that purpose, it is proposed to establishtunnels to one or more adjacent well bore casings 42. While variousknown methods may be employed for establishing such tunnels and thepresent invention is not limited to any particular means, the means tobe now described and the methods pertaining thereto are considered to beespecially suitable for purposes of this invention.

From the bottom of one or both of the casings 40 and 42 there arelaterally directed the nozzle portions 44 of the hydraulic tunnelingdevices towards the opposite well casing to which it is desired toextend a tunnel. Optionally, both nozzles may be operated simultaneouslyin order to drive two tunnel sections toward a junction with each other,or alternatively, one nozzle alone can be employed to drive the entiretunnel to the other well bore.

Figure 6 discloses an apparatus suitable for this tunneling operation.The casings 40 and/or 42 include the usual well tubing 46 which, at itslower end, has a curved laterally extending terminal portion 48terminating at the side of the casing and being positioned and directedagainst the face of the oil sand strata and in substantial alignmentwith the other well casing to which the tunnel is to be established.Slidable within the tubing 46 and its terminal portion 48 is a flexibleconduit 50 having upon its lower end the above mentioned nozzle portion44. A cable 52, operated in any desired manner, provides means wherebythe flexible conduit 50 may be moved downwardly in the tubing 46 andextended laterally from the terminal portion 48 thereof to thus feed thenozzle into the oil sand strata as the tunnel is being formed andprogresses toward the other well bore.

In the well bores, at the lower ends of each of the casings 40 and 42,there is provided an arcuate guard or shield 54 which is substantiallyconcentric with the lower portion of the curved terminal 48 of thetubing and which direct the return flow of the pressure medium into andup the casing 40 as illustrated by the arrows in Figure 6.

In contrast with the usual manner of merely supplying a fluid mediumunder pressure through the nozzle 44 and attempting to increase thepressure thereof until the same, by sheer force, penetrates the oil sandstrata and reaches the other well bore, or establishes a junction withthe other tunnel section being started from the well bore, the presentinvention in general consists in rendering the pressure of the fluidmedium more elfective to penetrate the strata by causing successivepressure fluctuations of the pressure medium at the face of the strataand within the interstices thereof.

These fluctuations subject the face of the strata and the face of thematerial within the interstices of the strata to pressures which arealternately greater and less than the pressure within the strata. Whenthe pressure of the pressure medium exceeds that within the strata, thelatter will be augmented or raised, especially in that portion nearerthe face of strata. When the converse condition exists, the internalpressure within the strata will forcefully burst or explode the face ofthe strata outwardly, disrupting the same.

This disrupting of the capillary formation of the strata is greatlyaugmented and hastened by increasing the extremes between the high andlow pressures applied to the strata; by increasing the surging of thepressure me dium within the pores of and against the strata by impartinghigh frequency vibrations to the pressure medium; and increasing theeroding action of the medium within the pores of the strata by thepreceding processes.

In initiating the tunneling operation, the fluid medium is suppliedunder pressure from any suitable source by the conduit 56 into thetubing 46 and discharge from the nozzle portion 44 against the face ofthe oil sand strata as illustrated. This pressure medium will cut intoand form a tunnel or channel in the oil sand strata, the materialremoved by the fluid medium being educted as indicated by the arrows inFigure 6 upwardly in the casing 40 and discharged from a conduit 60under the control of a valve 62 through a control or operating membersuch as a cam 64.

Obviously, if desired, the outfiowing pressure fluid from 60 may bereturned to the conduit 56 to cause a recirculation of the same duringthe tunneling operation.

As so far described, this circulation of the pressure medium will, inconformity with known procedures, cause some disruption of the strata.Regulation of the pressure in the conduit 56 or of the valve 62 or bothwill maintain any desired mean pressure upon the pressure medium.However, in addition to the circulation of the fluid me dium under wavesof various pressures, it is intended to render the excavating action ofthe same more effective as Well as more accurately directed andcontrolled by applying pulsations to the fluid medium and by imposinghigh frequency vibrations thereon, the character of the pulsations andthe vibrations being varied and controlled.

The casing 44) is provided with an impulse producing means in the formof a piston 72 reciprocable in a conduit 74 under the control of anactuating cam 76' or similar member, while the tubing 46 is providedwith an impulse producing piston 66, reciprocable in a conduit 68 underthe control of a cam 70 or other actuating means, and further with apressure release valve 76 operable in a conduit 78 under the control ofan actuating cam 80.

By periodic and/or adjustable manipulation of the pistons 66 or 72, apulsation or wave motion may be transmitted through the pressure mediumwhich functions as an elastic or closed hydraulic column. The rigidcolumn of the pressure medium will transmit the impulses or energyshocks, without substantial loss to the strata. There, the pressureimpulses pass from the denser transmitting medium to a more elasticresilient medium consisting of the oil particles and gas bubbles at theoil face of the strata, and produce a turbulent washing of the latterinto the formation. With the change of medium, the impulses areconverted to vibrations having a much greater amplitude and thisfacilitates the above mentioned washing and penetrating action.

By using both pistons 66 and 72, separate pulsations, each of apredetermined pattern or character may be separately produced andimposed upon the pressure medium to produce a resultant vibration orwave. It should be noted that these two separate pulsations may bevaried as to intensity, character and phase so as to reinforce, cancelor modify each other so that the resultant pulsation may have muchgreater extremes between its high and low pressure, may have portionscancelled out by interference and otherwise altered as desired.Moreover, the speed of travel of the wave pulsation of piston 66 to thenozzle and sand face is different from that of piston 72, since in thefirst instance the velocity of the medium is added thereto while in thelatter it is subtracted therefrom. This difference is utilized toproperly time and synchronize the peaks and lows of the two waves toobtain a resultant wave having desired predetermined peaks and valleys.

In applying this method of tunneling, it is intended that the fluidapplied to the sand strata from the casing 40 shall materially exceed inpressure the pressure existing within the capillary formation of the oilsand strata. Consequently, the fluid will tend to 'be driven outwardlyfrom the nozzle into this capillary formation assisted by the pulsationsand vibrations and toward the adjacent well casings. At the same time,pulsations of a similar character will be produced in the fluid beingapplied to the nozzle of the adjacent casings 42. The pulsation from thedriving casing 40, if opposite in phase to that of the pulling casing 42will guide and augment the penetrative effect, since the oil sand stratatherebetween will be subjected to a high pressure adjacent the casing 40at the same time that a greatly reduced pressure prevails at the casings42. This condition may be maintained for any desired length of time,this length of time being varied during the treating of the formation,and is found to be most effective for penetrating the oil sand strata,but will be periodically reversed, whereby the casings 42 become thedriving casings and the casing 40 becomes the pulling casing for theoperation. It will be evident that this cycle of reversing the pushingand pulling effect upon the opposite ends of the sand strata between thetwo casings will tend to extend the tunnel sections toward each otherunder the pressure impulses and high pressure conditions prevailing attheir nozzles, and the low pressure region created at one well will pullor guide the flow of pressure fluid from the high pressure region of theother well casing toward the low pressure region.

The effectiveness of this driving and guiding action upon the pressurefluid of the tunneling operation will be greatly augmented by theimposition of high frequency vibrations thereon of predeterminedcharacter. The above mentioned pistons will obviously be capable ofvariation in the extent and rate of their travel, to enable theattaining of any desired rate and amplitude of pulsation within thefluid medium.

The opening and subsequent sudden closing of the pressure mediumdischarge valves 62 and 76 with predetermined timing and adjustablerates of movement will set up, by a ram action, a hammering effect inthe fluid columns of the tubing 46 and of the casings 40 or 42. As iswell known, this hammering effect is capable of producing relativelyenormous and rapid pressure oscillations in the fluid column which willbe transmitted and directed by the nozzle portions 44. Theseoscillations will be imposed upon the above mentioned fluctuations andvibrations, and may be united and combined to augment the pressure peaksor drops to further increase their differences. By using the appropriatecombinations of one or both of the pistons and valves, an infinitevariety of resultant frequencies of pulsations or vibrations arepossible. The force and pressures exerted by the fluid medium upon theopposite faces of the oil strata between the two casings may thus be ofrelatively enormous magnitude and by virtue of the eomplemental actionof a pres sure peak upon one side of the strata simultaneously with apressure reduction on the other side, it is evident that the penetrativeeffect of the fluid medium into the capillary formation will betremendously increased.

As will be readily understood, the paths of travel of the fluid mediumwill be relatively wide adjacent the well casings from which theyoriginate, and will tend to thin out or narrow intermediate the wellcasings, due to the guiding and pulling effect of the reduced pressurearea upon the high pressure medium flowing from the other well casing.This path of travel is indicated in dotted lines in Figure 5 for aseries of well casings in which a aromas central casing is considered tobe acting as a driving casing for forcing tunnels to the four adjacentreceiving casings 42. It is contemplated, however, that each well casingin turn will function alternately as driving and receiving stations foreach of the adjacent well changes, thereby permitting the establishmentof tunnels simultaneously between a plurality of adjacent well bores.

In the arrangement of Figure 5, it is intended that any desired systemof control may be utilized to effect the above mentioned alternatingoperation of the driving and pulling force applied to the fluid medium,this feature of the invention being readily adaptable to a large numberof arrangements.

In accordance with the above described operation as suggested in Figure5, it will be readily seen that a plurality of nozzles 44 may beutilized in one or more of the casings in order to simultaneously tunneltoward a plurality of adjacent casings. Since, however, this applicationof the principles of this invention involves merely a duplication ofequipment, and constitutes no change in the fundamental principle andintent of the invention, further illustration and explanation is deemedto be unnecessary.

As hereinbefore described, it is believed apparent that it is entirelyfeasible to establish and create by the above mentioned hydraulicmechanism and operation any desired tunnels between selected well bores.These tunnels may be utilized as hereinbefore set forth for thereception of cutting means for undercutting the oil strata. However,this hydraulic operation may be utilized either in conjunction with themechanical cutting device previously set forth or alone and by itself asa cutting agent for undercutting, channeling, penetrating and disruptingthe oil and strata. In considering this inherent function of thehydraulic operation, the particular nature of the capillary formation ofthe oil strata should be particularly considered.

The period of high pressure of the fluid upon the face of the strata maybe maintained for any desired period of time as dictated by experienceto permit this increase of the pressure within the pores of theformation, at least in those pores contiguous to the face of theformation. It is contemplated that when the hydraulic operation is firststarted, the high pressure may be sustained for several days ifnecessary, while the vibrations and oscillations are being applied.However, as the strata formation is being attacked and penetrated andthe oil and gas deposits thereof are loosened, the duIation of the highpressure necessary to penetrate will decrease with intervals of as lowas a few minutes will be suflicient.

Obviously, this process will result in increasing the diameter of thepassages or tunnels produced by the tunneling device and this processwill be continued and can be continued as long as necessary to attaintunnels of the requisite diameter to permit passage of the previouslymentioned lead lines and floats therethrough and the drawing of thecutting device in the form of a cable thereafter.

Still further, however, if this tunneling, cutting and pulsating actionis continued sufficiently, it is evident that the entire sand formationmay be undercut and collapsed or disrupted, thus effectively breakingthe capillary lock and permitting the recovery of the oil depositstherein.

By virtue of the pulsating and high frequency vibration of the pressuremedium, it is evident that a surging and washing action of the gases andoil between the sand particles is effected which will efliciently stripboth the mobile and the immobile oil particles therefrom, renderingstill more efficient the oil recovery from the strata.

Moreover, I may in some instances introduce into the pressure medium andpresent at the oil and gas front in the strata inert gases such ascarbon dioxide and fluids which will liquefy or dissolve under the peakpressures of kit) the pressure medium whereby they will be carried intothe pores of the strata formation; and will vaporize or come out ofsolution when the pressure is reduced, to thereby assist in bursting andtearing the strata formation.

When the above described hydraulic operation is utilized in conjunctionwith the mechanical undercutting of the strata, the internal pressuringof the formation will render the same easier to cut by the movement ofthe cutting device across the face of the same so that upon movement ofsuch device, the particles of the formation adjacent thereto willreadily burst outward under their internal pressures upon weakening ofthe physical structure by the cutting device. This will result in anoutflow of oil, water and gas from the strata into the cut made by thecutting device, thereby producing a continuous yield of oil during thecutting operation; cleansing the cutting device by this outflow ofmaterial therefrom; and effecting a cleansing or scavenging of the cutitself by the outflow of material therefrom.

In some instances, I may apply fluid pressure into the formation inadvance of the cutting or undercutting operations. This applied pressurewill raise the internal pressure of the formation and cause a driving ofthe oil and gas deposits thereof toward the lower pressure of theweakened zone of the cutting.

For this purpose, as shown in Figure 3, I utilize an abandoned well orif necessary a new bore K to apply pressure, which may be of a pulsatingor vibrating nature, to the interior of the formation when the cuttingdevice is operating between the wells DABE as previously mentioned. Asthe cutting device advances along the strata, the pressure fluid isapplied to successive wells K and L. Thus, a pressure drive is appliedto the oil strata where it will be most effective in driving oil to thecutting and facilitate the cutting operation by bursting the face of thestrata at and during the cutting and by washing the same.

Set forth in the patent of C. E. Riestle, in, Patent No. 2,547,778,issued April 3, 1951, is a method for increasing the yield of oil fromoil bearing strata formations, wherein a portion of the strata isexpanded, lifted and fractured generally along horizontal planes ofcleavage, by applying hydraulic pressure through a well bore upwardlyagainst an undercut portion of the strata, and thus vertically raisingthe surrounding area of the strata.

The present invention contemplates an improvement of the method of theabove patent by not only hydraulically lifting and fracturing the stratabut simultaneously therewith more completely and readily establishing anenlargement of the generally annular drainage basin about a well bore bydisrupting the internal structure of the sand strata to increase thevolume of the basin; and will enable the limits of the basin to beenlarged along predetermined desirable directional lines of travel.

In addition, the actual process of enlarging the collecting basin isaccompanied by a more etfective and simultaneous withdrawing andstripping of the oil deposits from the oil sands by use of the foregoinghydraulic wave and vibrational effects to enable their collection in thebasin. Still further, this invention contemplates maintaining a minimumpressure in the basin during the above mentioned pulsations andvibrations to hold the same expanded while gravel is applied thereto tofill this space and assist in holding the raised strata in its elevatedposition, thereby facilitating drainage of the oil.

In any of the hereinbefore set forth methods, it is possible tointroduce gravel into the formation during and without interrupting thehydraulic operation. This may be conveniently effected by the apparatusof Figure 6, wherein a conduit 57 comunicates with the interior of thetubing 46. A gravel hopper 59 having any suitable means for filling thesame, such as the removable cover 61, discharges gravel into the conduitunder control of the valve 63.

The turbulence, vibration and velocity of fluid of the fluid pressuremedium in and from the tubing 46, conaxially reciprocable in a valvechamber 73 in the casing 65. Opposite ends of the casing have valveseats 75 and 77, respectively, engageable by the valves 69 and 71. Thestem is longitudinally slotted at 79 to receive a stationary guide lug81 carried by the casing which prevents rotation of the valve.

An operating lever 83 extends through the side of easing I 65 into ahousing 85 and has one end swiveled at 87 to a lug on the valve stem andthe other end pivoted to a rod 89. The latter extends outwardly of thehousing 85 and into a housing 91.

In the housing 91 is a control member, not shown, of any desiredcharacter which is connected to the rod 89 and extends into the conduit56. The control member is responsive to variations in pressure in theconduit 56 both above or below predetermined limits for closing one ofthe valve seats. Thus, if a pressure wave travels up the conduit 56,which might damage the pump supplying fluid to the conduit, the controlmember engages the valve 69 with its seat 75. Conversely, if thepressure within the conduit is suddenly lowered, the valve 71 will becaused to engage the seat 77, as illustrated in Figure 7. Havingdescribed the invention, what is claimed as new 1s:

1. A method of cutting an oil bearing strata of a subterranean formationwhich comprises; providing a plurality of bores each extending into thestrata, providing a tunnel in the strata connecting a pair of the bores,positioning a cutting device in said tunnel and against the face of thestrata, applying motion to the cutting device through said pair of boresto penetrate the face of the strata, ap-

plying through another of said bores lying within the strata being cut afluid into the strata under a pressure in excess of the internalpressure of the strata and thereby increase the internal pressure inthat portion of the strata to which the cutting device is appliedwhereby to assist the cutting of the strata.

2. A method of cutting an oil bearing strata of a subterranean formationwhich comprises; providing a plurality of bores each extending into thestrata, providing a pair of intersecting, angularly related tunnels inthe strata each connecting a single one of the bores with one of a pairof adjacent bores, positioning a cutting device in said intersectingtunnels and against the face of the strata in operative contacttherewith, operating through the pair of adjacent bores the cuttingdevice to penetrate the strata, applying fluid into another of saidbores lying within the strata being out under a pressure exceeding theinternal pressure of the "strata whereby to raise the internal pressureof the strata at the cutting device and thereby assist the latter incutting the strata.

3. The method of claim 2 including the step of fluctuating the pressureof the fluid.

4. That method of reclaiming oil from an oil bearing strata of an oilfield which includes the steps of establishing tunnels in the stratabetween a first well bore and two adjacent well bores, inserting acutting device in said tunnels with portions of said cutting deviceextending into said adjacent well bores and imparting movement to saidcutting device to undercut the face of the strata exposed in saidtunnels, and raising the internal pressure within the strata by theintroduction of a fluid under pressure through an additional bore lyingwithin the strata in advance of the cutting device.

' 5. A method of removing oil deposits from a petroliferous strata whichconsists of establishing vertical bores into the interior of the strata,connecting said bores by horizontally extending passages in said strata,introducing a cutting device through said bores into said passages,operating said cutting device to produce separation of the strata alonga horizontal plane, permitting the oil in the strata to drain into theseparation, recovering the oil from the separation, and raising theinternal pressure within the strata by the introduction of a fluid underpressure through an additional bore lying within the strata in advanceof the cutting device.

6. The method of claim 4 wherein said fluid introduced under pressureincludes a liquifiable gas.

" 7. The method of claim 1 wherein said applied fluid includes aliquifiable gas.

8. The method of claim 4 including the step of causing -collapse of theundercut portion of said strata.

9. The method of claim 1 including the step of causing collapse of theundercut portion of said strata.

References Cited in the file of this patent UNITED STATES PATENTS Re.23,381 Bodine June 26, 1951 753,092 Neukirch Feb. 23, 1904 1,826,371Spindler Oct. 6, 1931 2,104,488 Kennedy et a1. Jan. 4, 1938 2,115,378Wolf Apr. 26, 1938 2,163,650 Weaver June 27, 1939 2,217,749 Hewitt Oct.15, 1940 2,229,540 Zublin Jan. 21, 1941 2,251,916 Cross Aug. 12, 19412,308,517 Konnerth Jan. 19, 1943 2,331,072 Hansen et al. Oct. 5, 19432,347,769 Crites May 2, 1944 2,354,570 Benckenstein July 25, 19442,383,496 Nebolsine Aug. 28, 1945 2,398,123 Sowers Apr. 9, 19462,546,252 Bankson Mar. 27, 1951 2,547,778 Reistle Apr. 3, 1951 2,554,005Bodine May 22, 1951 2,562,545 Gogolick et a1 July 31, 1951 2,670,943Vogel Mar. 2, 1954 2,690,325 Dismukes Sept. 28, 1954 2,700,422 BodineJan. 25, 1955

1. A METHOD OF CUTTING AN OIL BEARING STRATA OF A SUBTERRANEAN FORMATIONWHICH COMPRISES; PROVIDING A PLURALITY OF BORES EACH EXTENDING INTO THESTRATA, PROVIDING A TUNNEL IN THE STRATA CONNECTING A PAIR OF THE BORES,POSITIONING A CUTTING DEVICE IN SAID TUNNEL AND AGAINST THE FACE OF THESTRATA, APPLYING MOTION TO THE CUTTING DEVICE THROUGH SAID PAIR OF BORESTO PENETRATE THE FACE OF THE STRATA, APBEING CUT A FLUID INTO THE STRATAUNDER A PRESSURE IN EXCESS OF THE INTERNAL PRESSURE OF THE STRATA ANDTHEREBY INCREASE THE INTERNAL PRESSURE IN THAT PORTION OF THE STRATA TOWHICH THE CUTTING DEVICE IS APPLIED WHEREBY TO ASSIST THE CUTTING OF THESTRATA.